A heart of gold and a personality to match. What you see is what you get.
An ambitious go-getter. I'm attracted to people who set big goals and put all their effort into pursuing them. Even if your life's dream is to become the world's greatest thumb-wrestler, I totally dig it.
People could rationally decide that prolonged relationships take up too much time and effort and that they'd much rather do other kinds of things. But most people are afraid of rejection.